Extended Abstract (92K)16B.2
Vortex alignment on the f and beta plane
Robert W. Jones, University of Miami/CIMAS, Miami, FL; and H. E. Willoughby
Resonant damping theory of Schecter, Montgomery, and Reasor has been applied to tilted hurricane like vortices by means of two layer linear and nonlinear spectral tracking models that decend from the one layer models of Willoughby. Although the theory is barotropic, it reasonably applies to nearly baroclinic initial states in which the winds are the same in each layer, while the depth gyres differ. Our initial vortices have a minimum of the symmetric potential vorticity. Thus, resonant damping or amplification may occur depending upon which side of the PV minimum the critical radius where the cyclonic corotation of the vortices matches the rotation of the vortex winds occurs. On the f-plane linear and nonlinear results generally lead to the same conclusion consistant with results of Reasor and Montgomery. However, on the beta plane nonlinear interactions change the base state tangential winds and PV, so that vortices that align on the f-plane will become unstable on the beta plane. This process occurs over a period of a few days for a minimal hurricane. Enviornmental shear may also change aligning vortices into misaligning for a nonlinear model.
Session 16B, Convection, waves, and precipitation VII
Friday, 7 May 2004, 8:00 AM-9:30 AM, Napoleon I Room
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